1. Technical Field
The present invention relates to an improved internal combustion engine exhaust system. More specifically, it relates to an exhaust system in which at least a portion of the system has a parallelogram-shaped cross-section.
2. Background
The performance and efficiency of internal combustion engines depends on the efficient movement of gases through the engine, from the introduction of air and fuel through the intake ports into the cylinders of the engine to exhaust of the combustion by-products through the exhaust ports. The exhaust system performs a critical role in this process and has a significant impact on efficiency of the engine. The exhaust system operates to provide complete and efficient xe2x80x9cscavengingxe2x80x9d of the exhaust gases from the cylinder, in part by providing for low pressure downstream from the cylinders (e.g., back pressure). Effective scavenging of the cylinders results in the use of less power to xe2x80x9cpumpxe2x80x9d exhaust gases out of the cylinder. One method known in the art for facilitating scavenging of the cylinders is to reduce back pressure by reducing the pressure drop through the exhaust system.
A typical exhaust system known in the art includes a header flange, conduits, and a collector. Both the conduits and the collector are round in lateral cross-section. The header flange includes an appropriate number of openings for coupling to the engine exhaust ports. For example, for a four cylinder engine, the header flange includes four openings for coupling to the exhaust ports of the engine. The system includes four conduits, one corresponding to each opening on the header flange. The collector in one embodiment includes a megaphone or tapered section for reflecting pulses from the engine back toward the exhaust ports.
In a prior art device having conduits and collectors having a round lateral cross-section, the mechanics of fluid flow through a circular tube mandate that the exhaust gases will swirl or move in a spiral fashion as they traverse the exhaust system. The swirl motion results because the volume of the exhaust gases exceeds the volume of the circular tube. This swirl motion increases the residence time of the exhaust gases and the contact with the walls of the exhaust system, which results in a greater pressure drop through the system. This greater pressure drop results in less than optimal engine performance.
In a typical prior art exhaust system, the conduits and collectors have a fixed, non-adjustable length. For example, a typical exhaust system for a four cylinder engine has four conduits of non-adjustable length, possibly including fixed-length tapered sections. The fixed length systems cannot be adjusted to achieve optimal levels of engine performance.
There is a need in the art for an exhaust system having improved scavenging capabilities and reduced backpressure that results in increased engine performance. There is a further need for a device adapted to have an adjustable length to allow for optimal engine performance levels.
The present invention, in one embodiment, is an exhaust system for conducting exhaust gases from an internal combustion engine having at least one cylinder with at least one corresponding exhaust port. The exhaust system includes an exhaust header flange adapted for coupling to the exhaust port of the internal combustion engine. At least one conduit is coupled to the header flange, the conduit having a generally parallelogram-shaped cross-section. The conduit operates to conduct the exhaust gases from the exhaust port. A collector having a generally parallelogram-shaped cross-section is coupled to the conduit.
In another embodiment of the present invention, the exhaust system includes a tapered insert sized to fit within the enclosed space defined by the collector. The tapered insert includes a first end having a larger cross-sectional area than a second end.
While multiple embodiments are disclosed, still other embodiments of the present invention will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the invention. As will be realized, the invention is capable of modifications in various obvious aspects, all without departing from the spirit and scope of the present invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive.